A longitudinal study of atrazine and 2,4-D exposure and oxidative stress markers among iowa corn farmers

Abstract

Reactive oxygen species, potentially formed through environmental exposures, can overwhelm an organism's antioxidant capabilities resulting in oxidative stress. Long-term oxidative stress is linked with chronic diseases. Pesticide exposures have been shown to cause oxidative stress in vivo. We utilized a longitudinal study of corn farmers and non-farming controls in Iowa to examine the impact of exposure to the widely used herbicides atrazine and 2,4-dichlorophenoxyacetic acid (2,4-D) on markers of oxidative stress. 225 urine samples were collected during five agricultural time periods (pre-planting, planting, growing, harvest, off-season) for 30 farmers who applied pesticides occupationally and 10 controls who did not; all were non-smoking men ages 40-60. Atrazine mercapturate (atrazine metabolite), 2,4-D, and oxidative stress markers (malondialdehyde [MDA], 8-hydroxy-2'-deoxyguanosine [8-OHdG], and 8-isoprostaglandin-F2α [8-isoPGF]) were measured in urine. We calculated β estimates and 95% confidence intervals (95%CI) for each pesticide-oxidative stress marker combination using multivariate linear mixed-effect models for repeated measures. Farmers had higher urinary atrazine mercapturate and 2,4-D levels compared with controls. In regression models, after natural log transformation, 2,4-D was associated with elevated levels of 8-OHdG (β = 0.066, 95%CI = 0.008-0.124) and 8-isoPGF (β = 0.088, 95%CI = 0.004-0.172). 2,4-D may be associated with oxidative stress because of modest increases in 8-OHdG, a marker of oxidative DNA damage, and 8-isoPGF, a product of lipoprotein peroxidation, with recent 2,4-D exposure. Future studies should investigate the role of 2,4-D-induced oxidative stress in the pathogenesis of human diseases. Environ. Mol. Mutagen. 58:30-38, 2017. © 2016 Wiley Periodicals, Inc.